In the European patent EP 0 422 093, a yarn storage device is described consisting of a number of yarn storage units arranged next to one another in the form of elongate tubes in which yarn is stored in a wound-up state. Each of these tubes has an open entry side along which yarn is supplied to the yarn supply and an open output side via which the yarn leaves the tube and is taken to a yarn-processing device. The yarn loader is designed to be positioned at the entry side of a selected tube in order to replenish the yarn supply in said tube with the desired yarn. Replenishing can be carried out without interrupting the fabric-manufacturing process since new yarn can be added by connecting the free end of the yarn to be added (by tying a knot or ‘splicing’) to the free end of the yarn supply present in the tube.
Replenishing is carried out after the yarn ends have been connected, by forming yarn windings by means of a rotating head in the tube. The new windings push the yarn supply which is already present further into the tube.
In practice, it has been found that this way of producing windings is not suitable for every type of yarn. Only with yarns having a sufficient stiffness and roughness do the windings maintain their shape so that the windings adjoin one another without the risk of entanglement. This method does not provide a solution for yarns which per se have a limited stiffness or whose structure is smoother, because the windings are not formed in an orderly fashion or do not adjoin one another tightly, so that when they are removed at the exit side of the tube, knots and/or entanglements are formed which cannot be untangled.
In the multicoloured weaving and tufting of carpet, pile warp yarns of different colours have to be supplied to the weaving or tufting device. The consumption of said pile warp yarns depends on the design of the carpet and is thus usually not even and not identical for each pile warp thread in the fabric. As a result, the yarn storage device has to contain a separate yarn supply for each different pile warp yarn. It is known to achieve this by supplying the different yarns from respective bobbins which have been placed in a bobbin creel.
Such a bobbin creel often has to contain many thousands of bobbins and thus occupies a large amount of space, while the total amount of yarn in such a bobbin creel is also considerable. Replenishing yarns in the bobbin creel and changing yarns for carpet or velvet weaving machines is currently still done manually: (i) the used-up bobbins have to be removed from the creel and new ones have to be fitted; (ii) the thread from the new bobbin has to be tied to the previous thread and the thread has to be introduced into a guide; (iii) finally, the threads have to be retensioned again by placing small weights on the thread. In addition, thread breakages also have to be repaired manually.
The large amount of work which has to be carried out manually with a bobbin creel takes up a considerable amount of time as a result of which, the machine is non-productive for a long period of time. This is very disadvantageous for the overall efficiency of the weaving machine. In addition, this work results in significant labour costs.